Spandrel

The human brain is a spandrel? Ok, says the guy who used his brain to think that...

If the human chin is a spandrel, how will we play the violin?

Sculptured votive wreaths, six in all, are hung between the capitals of the columns and the spandrel of the arches.

Usual practice then builds a wall above each curved end of the arch, known as a spandrel, which directly joins the bridge's sidewalls. […] With sidewalls and spandrels in place, you can fill the space between them with material up to the height of the bridge deck, and then place the road or railway on top.

2002, Kerstin Lang, Seismic Vulnerability of Existing Buildings, vdf Hochschulverlag AG, page 25, Due to the fact that the walls are joined by floors and spandrels, a coupling effect is produced. Depending on the extent of the spandrels, this coupling effect will be bigger or smaller.

Another type of theory emphasises the sometimes accidental nature of evolution. A spandrel is a structure arising as a by-product of some other architectural configuration. In evolutionary terms, a spandrel is some trait of an organism which emerges not through direct adaptionist or exaptationist means, but rather as a side effect of some other evolutionary development.